1. Field of the Invention
The present invention relates to a bidirectional optical communication apparatus and an optical remote control apparatus using this communication apparatus.
2. Description of the Related Art
Conventionally, a remote control apparatus is generally added to an audio visual apparatus such as a television or a CD player, thereby enabling various operations such as switching of television display channels, switching between recording and play and stop, selection from CDs, and turning-on and -off of the apparatus body despite a distance from the main apparatus body.
Such remote control apparatuses generally use infrared rays and are each composed of a set of a remote operation section and a remote-controlled section. In addition, the remote operation section is located on the operator""s side, while the remote-controlled section is built into the audio visual apparatus (main apparatus) body. Furthermore, as shown in, for example, FIG. 2, a remote operation section 110 located on the operator"" side has an input operation section 111, a control section 112, and a transmission section 113. In addition, a remote-controlled section 120 built into the apparatus main body has a reception section 121 and a control section 122.
In the remote operation section 110, the input operation section 111 comprises a plurality of momentary switches to output to the control section 112 a switch signal indicating which switch has been pressed.
The control section 112 is composed of a well-known CPU, and based on the switch signal received from the input control section 111, creates a transmitted instruction signal to output it to the transmission section 113.
The transmission section 113 is composed of an infrared light-emitting diode and a diode drive circuit, and receives the instruction signal from the control section 112 to drive the infrared light-emitting diode based on this signal in order to radiate it to the external space as an optical signal.
In the remote-controlled section 120, the reception section 121 comprises an infrared photodiode and at least an amplifier etc. (ex. A filter, and a comparator), and receives the infrared light from the remote operation section 110 to output an electric signal corresponding to the infrared signal.
The control section 122 receives the electric signal output from the reception signal 121, and based on this signal, decodes the instruction sent from the remote operation section 110 to output it to a main control section 131 in a main apparatus body 130.
The main control section 131 of the main apparatus body 130 then controls an operation such as switching of the television display channels or turning-on or -off of the power according to the instruction received from the remote-controlled section 120.
Such a conventional remote control apparatus, however, transmits signals in only one direction, that is, from the remote operation section 110 to the remote-controlled section 120. Thus, information such as the operational condition of the main apparatus body 130 cannot be displayed on the remote operation section 110 on the operator""s side.
To display information such as the operational condition of the main apparatus body 130 on the remote operation section 110, the information must be transmitted from the remote-controlled section 120 to the remote operation section 110. Thus, as shown in FIG. 3, the remote operation section 110 may be provided with a reception section 114 and a display section 115 while the remote-controlled section 120 may be provided with a transmission section 123. This configuration, however, has the following problems.
Half-duplex and full-duplex communication methods are known as bidirectional communication methods, but the half-duplex communication method requires a protocol for switching between transmission and reception. This results in complicated communication control and difficulties in achieving long continuous data communication due to the incapability of reception during transmission.
In addition, although the full-duplex communication method enables transmission and reception to be simultaneously executed to enable long continuous data communication, a light-emitting element and a light-receiving element are located adjacent to each other in order to reduce the size of the apparatus. Thus, as shown in FIG. 4, an infrared ray radiated from the transmission section is incident on the reception section, causing malfunction. Another cause of malfunction is the incidence on the reception section of an infrared ray radiated from the transmission section and reflected by walls of the room a number of times. One means for preventing such malfunction is to improve the light-emitting directionality of the light-emitting element and the light incidence directionality of the light-receiving element. This means eliminates the incidence on the light-receiving element of light radiated from the light-emitting element despite the proximity between the light-emitting and -receiving elements. In this case, however, the optical axes of two bidirectional lines must be aligned accurately, and this operation is very cumbersome and requires a large amount of time and labor. Therefor, these methods are not so practical.
It is an object of the present invention to provide a bidirectional optical communication apparatus that does not require complicated communication control or accurate optical-axis alignment, as well as an optical remote control apparatus using this communication apparatus.
The present invention provides a bidirectional optical communication apparatus composed of a set of a first device comprising a first transmission section and a first reception section and a second device comprising a second transmission section and a second reception section, wherein the first and second devices use light to communicate data in both directions.
In this configuration, the first transmission section of the first device comprises a first light-emitting element that emits light corresponding to a transmitted digital signal and a first linear-polarization plate located on the light emission side of the fist light-emitting element according to the present invention. The first reception section comprises a first light-receiving element, and a second linear-polarization plate provided on the light incidence side of the first light-receiving element and located in such a way as to pass linear polarization having a polarization surface orthogonal to the polarization surface of linear polarization passing through the first linear-polarization plate.
Furthermore, the second transmission section of the second device comprises a second light-emitting element that emits light corresponding to a transmitted digital signal and a third linear-polarization plate located on the light emission side of the second light-emitting element to pass linear polarization having the plane of polarization of linear polarization passing through the second linear-polarization plate. The second reception section comprises a second light-receiving element; and a fourth linear-polarization plate provided on the light incidence side of the second light-receiving element and located in such a way as to pass linear polarization having the same plane of polarization as that of linear polarization passing through the first linear-polarization plate.
According to this bidirectional optical communication apparatus, when the first device communicates data to the second device, a transmitted digital signal is input to the first light-emitting element of the first transmission section, and the first light-emitting element emits light based on the digital signal.
Furthermore, the first linear-polarization plate radiates the light emitted from the first light-emitting element to the external space as linear polarization. The linear polarization radiated to the external space via the first linear-polarization plate (hereafter referred to as a xe2x80x9cfirst signal lightxe2x80x9d) reaches the second device, passes through the fourth linear-polarization plate of the second reception section, and enters the second light-receiving element. Then, the second light-receiving element converts the first signal light into an electric signal and outputs this signal. The electric signal output from the second light-receiving element mostly corresponds to the digital signal communicated from the first device to the second device.
On the other hand, when the second device communicates data to the first device, a transmitted digital signal is input to the second light-emitting element of the second transmission section, and the second light-emitting element emits light based on the digital signal. Furthermore, the third linear-polarization plate radiates the light emitted from the second light-emitting element to the external space as linear polarization.
The linear polarization radiated to the external space via the third linear-polarization plate (hereafter referred to as a xe2x80x9csecond signal lightxe2x80x9d) reaches the first device, passes through the second linear-polarization plate of the first reception section, and enters the first light-receiving element. Then, the first light-receiving element converts the second signal light into an electric signal and outputs this signal. This electric signal mostly corresponds to the digital signal communicated from the second device to the first device.
In addition, the polarization surface of linear polarization radiated to the external space from the first transmission section of the first device is orthogonal to the polarization surface of linear polarization radiated to the external space from the second transmission section of the second device. This configuration prevents the linear polarization radiated from the first transmission section from passing through the second linear-polarization plate of the first reception section while preventing the linear polarization radiated from the second transmission section from passing through the fourth linear-polarization plate of the second reception section. This configuration thus precludes a mixture of these two signal lights from being received to prevent malfunction resulting from such a mixture.
This configuration also obviates the need to improve the light-emitting directionality of the light-emitting element and the light incidence directionality of the light-receiving element to eliminate the needs for cumbersome optical-axis alignment. Consequently, data can be communicated using either the half-duplex or full-duplex communication method by simply effectively opposing the first and second devices to each other, so this configuration is practical. In addition, using the full-duplex communication method, long continuous data transfer can be easily achieved without the needs for complicated protocol control.
In addition, according to another configuration of the present bidirectional optical communication apparatus, the first transmission section of the first device comprises a first light-emitting element that emits light corresponding to a transmitted digital signal, a first linear-polarization plate located on the light emission side of the first light-emitting element, and a first wavelength plate on which linear polarization from the first linear-polarization plate is incident to emit circular or elliptic polarization in one of the rotational directions.
The first reception section comprises a first light-receiving element; a second wavelength plate provided on the light incidence side of the first light-receiving element and on which circular or elliptic polarization in the other rotational direction is incident to emit linear polarization; and a second linear-polarization plate provided between the first light-receiving element and the second wavelength plate in such a way as to pass linear polarization from the second wavelength plate to allow it to enter the first light-receiving element.
In addition, the second transmission section of the second device comprises a second light-emitting element that emits light corresponding to a transmitted digital signal, a third linear-polarization plate located on the light emission side of the second light-emitting element, and a third wavelength plate on which linear polarization from the third linear-polarization plate is incident to emit circular or elliptic polarization in the other rotational direction. Furthermore, the second reception section comprises a second light-receiving element, a fourth linear-polarization plate provided on the light incidence side of the second light-receiving element, and a fourth wavelength plate located on the light incidence side of the fourth linear-polarization plate and on which the circular or elliptic polarization from the first wavelength plate is incident to emit linear polarization passing through the fourth linear-polarization plate.
According to this bidirectional optical communication apparatus, when the first device communicates data to the second device, a transmitted digital signal is input to the first light-emitting element of the first transmission section, and the first light-emitting element emits light based on the digital signal. Moreover, the first linear-polarization plate converts light from the first light-emitting element into linear polarization, and the first wavelength plate radiates this linear polarization to the external space as circular or elliptic polarization.
The circular or elliptic polarization radiated to the external space via the first wavelength plate (hereafter referred to as the xe2x80x9cfirst signal lightxe2x80x9d) reaches the second device, where the fourth wavelength plate of the second reception section converts it into linear polarization. This linear polarization passes through the fourth linear-polarization plate to enter the second light-receiving element. Then, the second light-receiving element converts the first signal light into an electric signal and outputs this signal. This electric signal mostly corresponds to the digital signal communicated from the first device to the second device.
On the other hand, when the second device communicates data to the first device, a transmitted digital signal is input to the second light-emitting element of the second transmission section, and the second light-emitting element emits light based on the digital signal. Moreover, the third linear-polarization plate converts light from the second light-emitting element into linear polarization, and the third wavelength plate radiates this linear polarization to the external space as circular or elliptic polarization.
The circular or elliptic polarization radiated to the external space via the third wavelength plate (hereafter referred to as the xe2x80x9csecond signal lightxe2x80x9d) reaches the first device, where the second wavelength plate of the first reception section converts it into linear polarization. This linear polarization passes through the second linear-polarization plate to enter the first light-receiving element. Then, the first light-receiving element converts the second signal light into an electric signal and outputs this signal. This electric signal mostly corresponds to the digital signal communicated from the second device to the first device.
In addition, the rotational direction of the circular or elliptic polarization radiated to the external space from the first transmission section of the first device is opposite to the rotational direction of the circular or elliptic polarization radiated to the external space from the second transmission section of the second device. This configuration prevents the circular or elliptic polarization radiated from the first transmission section from being incident on the first light-receiving element of the first reception section. It also prevents the circular or elliptic polarization radiated from the second transmission section from being incident on the second light-receiving element of the second reception section. This configuration thus precludes a mixture of these two signal lights from being received to prevent malfunction resulting from such a mixture.
Furthermore, this configuration eliminates the need to improve the light-emitting directionality of the light-emitting element and the light incidence directionality of the light-receiving element, thereby obviating the needs for cumbersome optical-axis alignment. Consequently, data can be communicated using either the half-duplex or full-duplex communication method by simply effectively opposing the first and second devices to each other, so this configuration is practical. In addition, using the full-duplex communication method, long continuous data transfer can be easily achieved without the needs for complicated protocol control.
In another configuration of the bidirectional optical communication apparatus according to the present invention, the first transmission section of the first device comprises a first light-emitting element that emits light corresponding to a transmitted digital signal. The first reception section comprises a first and a second light-receiving elements; a first linear-polarization plate provided on the light incidence side of the first light-receiving element; a second linear-polarization plate provided on the light incidence side of the second light-receiving element; a first wavelength plate located on the light incidence side of the first linear-polarization plate and on which circular or elliptic polarization in one of the rotational directions is incident to emit linear polarization passing through the first linear-polarization plate; a second wavelength plate located on the light incidence side of the second linear-polarization plate and on which circular or elliptic polarization in the other rotational direction is incident to emit linear polarization passing through the second linear-polarization plate; and a subtraction circuit for receiving the electric signals output from the first and second light-receiving elements to output the difference between these electric signal levels.
In addition, the second transmission section of the second device comprises a second light-emitting element that emits light corresponding to a transmitted digital signal, a third linear-polarization plate located on the light emission side of the second light-emitting element, and a third wavelength plate on which linear polarization from the third linear-polarization plate is incident to emit circular or elliptic polarization in one of the rotational directions. Moreover, the second reception section comprises a third light-emitting element; a fourth linear-polarization plate provided on the light incidence side of the third light-receiving element; and a fourth wavelength plate located on the light incidence side of the fourth linear-polarization plate and on which circular or elliptic polarization in the other rotational direction is incident to emit linear polarization passing through the fourth linear-polarization plate.
According to this bidirectional optical communication apparatus, when the first device communicates data to the second device, a transmitted digital signal is input to the first light-emitting element of the first transmission section, and light (hereafter referred to as the xe2x80x9cfirst signal lightxe2x80x9d) is emitted to the external space from the first light-emitting element based on the digital signal. The first signal light is not polarized.
The first signal light radiated from the first device reaches the second device, where the fourth wavelength plate of the second reception section converts this light into various linear polarizations. Only the relevant components of these linear polarizations pass through the fourth linear-polarization plate to enter the third light-receiving element. Then, the third light-receiving element converts the first signal light into an electric signal and outputs this signal. This electric signal mostly corresponds to the digital signal communicated from the first device to the second device.
On the other hand, when the second device communicates data to the first device, a transmitted digital signal is input to the second light-emitting element of the second transmission section, and the second light-emitting element emits light based on the digital signal. Moreover, the third linear-polarization plate converts light from the second light-emitting element into linear polarization, and the third wavelength plate radiates this linear polarization to the external space as circular or elliptic polarization in one of the rotational directions.
The circular or elliptic polarization in one of the rotational directions radiated to the external space via the third wavelength plate (hereafter referred to as the xe2x80x9csecond signal lightxe2x80x9d) reaches the first device, where the first wavelength plate of the first reception section converts this light into linear polarization. This linear polarization passes through the first linear-polarization plate to enter the first light-receiving element. At this point, natural light scattering in the external space is also incident on the first wavelength-plate. Then, only the relevant components of such light are converted into linear polarization passing through the first linear-polarization plate, which then enters the first light-receiving element. This polarization acts as a noise component.
In addition, the second signal light and natural light are incident on the second wavelength plate of the first reception section, where the second wavelength plate coverts these lights into linear polarization. Only the relevant components of the natural light, that is, only the components polarized circularly or elliptically in the other rotational direction are converted into the linear polarization that can pass through the second linear-polarization plate. The second signal light is converted into linear polarization that cannot pass through the second linear-polarization plate.
Furthermore, electric signals output from the first and second light-receiving elements are input to the subtraction circuit, which then outputs an electric signal having the level of the difference between these two electric signal levels. This configuration removes those components of natural light which are commonly present in the output signals from the first and second light-receiving elements, that is, the noise components. As a result, the electric signal output from the subtraction circuit mostly corresponds to the digital signal communicated from the second device to the first device.
In addition, if the first signal light radiated to the external space from the first transmission section of the first device is incident on the first reception section, it is equivalently incident on both the first and second wavelength plates. Thus, the subtraction circuit removes this light as in the natural light.
Moreover, since in the second reception section of the second device, the fourth wavelength plate and fourth linear-polarization plate are provided on the light incidence side of the third light-receiving element, only those components of the first signal light and natural light incident on the fourth wavelength plate which are polarized circularly or elliptically in the other rotational direction are incident on the third light-receiving element. Thus, even if the second signal light emitted from the second transmission section is incident on the second reception section, it is converted into linear polarization that cannot pass through the fourth linear-polarization plate.
This configuration precludes the first reception section from changing the light radiated from the first transmission section (the first signal light) into an electric signal, while precluding the circular or elliptic polarization radiated from the second transmission section (the second signal light) from being incident on the third light-receiving element of the second reception section.
This configuration thus precludes a mixture of these two signal lights from being received to prevent malfunction resulting from such a mixture.
This configuration also obviates the need to improve the light-emitting directionality of the light-emitting element and the light incidence directionality of the light-receiving element to eliminate the needs for cumbersome optical-axis alignment. Consequently, data can be communicated using either the half-duplex or full-duplex communication method by simply effectively opposing the first and second devices to each other, so this configuration is practical. In addition, using the full-duplex communication method, long continuous data transfer can be easily achieved without the needs for complicated protocol control.
In addition, according to the present invention, the bidirectional optical communication apparatus uses a first and a second light-emitting elements emitting infrared rays that are attenuated less significantly in the atmosphere than visible radiation, and a first and a second light-receiving elements that receive infrared rays to convert them into an electric signal, thereby reducing the attenuation of signals in the communication between the first and second devices to increase the communication distance.
Furthermore, according to the present invention, the first to fourth wavelength plates comprise quarter wavelength plates and the optical signal transmitted between the first and second devices comprises circular polarization, thereby preventing the variation of the reception level caused by the relative rotational angles of the transmission and reception sections and removing disturbing light noise. This configuration enables only the transmitted digital signal to be obtained and substantially reduces the effect of disturbing light noise compared to the prior art, thereby increasing the communication distance.
The present invention also configures an optical remote control apparatus using the above bidirectional optical communication apparatus.
This optical remote control apparatus is composed of a set of a remote operation section located on the operator""s side and a remote-controlled section provided in the main apparatus to be remote-controlled, wherein the remote operation section and the remote-controlled section use light to communicate instructions or information in both directions to remote-control the main apparatus.
According to a basic configuration of the present invention, the remote operation section comprises a first transmission section, a first reception section, an Input/Output (I/O) operation section, a first control section, and a display section.
The first transmission section comprises a first light-emitting element that receives a transmitted digital signal from the first control section to emit light corresponding to this digital signal; and a first linear-polarization plate located on the light emission side of the first light-emitting element.
The first reception section comprises a first light-receiving element; and a second linear-polarization plate provided on the light incidence side of the first light-receiving element and located in such a way as to pass linear polarization having a polarization surface orthogonal to the polarization surface of linear polarization passing through the first linear-polarization plate.
The I/O operation section comprises an instruction input means through which the operator inputs a control instruction.
The first control section comprises a transmit signal generation means for generating a digital signal corresponding to an instruction input using the instruction input means and outputting this digital signal to the first transmission section as a transmitted digital signal, an information decoding means for decoding receive information from an electric signal output from the first reception section, and a display control means for displaying on the display section the information decoded by the information decoding means.
The remote-controlled section comprises a second transmission section, a second reception section, and a second control section.
The second transmission section comprises a second light-emitting element that emits light corresponding to a transmitted digital signal and a third linear-polarization plate located on the light emission side of the second light-emitting element to pass linear polarization having the plane of polarization of linear polarization passing through the second linear-polarization plate.
The second reception section comprises a second light-receiving element; and a fourth linear-polarization plate provided on the light incidence side of the second light-receiving element and located in such a way as to pass linear polarization having the same plane of polarization as that of linear polarization passing through the first linear-polarization plate.
The second control section comprises a transmit signal generation means for generating a digital signal corresponding to information communicated to the remote operation section and outputting this digital signal to the second transmission section as a transmitted digital signal, an instruction decoding means for decoding an electric signal output from the second reception section, into a control instruction, and an operation control means for controlling the operation of the main apparatus to be controlled based on the control instruction decoded by the instruction decoding means.
According to this optical remote control apparatus, when the remote operation section communicates an instruction to the remote-controlled section and if the operator inputs an arbitrary instruction for the main apparatus via the instruction input means of the I/O operation section, then the transmit signal generation means of the first control section generates a digital signal corresponding to the instruction. This digital signal is input to the first light-emitting element of the first transmission section, and the first light-emitting element emits light based on the signal.
Moreover, the first linear-polarization plate radiates the light emitted from the first light-emitting element to the external space as linear polarization.
The linear polarization radiated to the external space via the first linear-polarization plate (hereafter referred to as the xe2x80x9cfirst signal lightxe2x80x9d) reaches the remote-controlled section, passes through the fourth linear-polarization plate of the second reception section, and enters the second light-receiving element. Then, the second light-receiving element converts the first signal light into an electric signal and outputs this signal. This electric signal mostly corresponds to the digital signal communicated from the remote operation section to the remote-controlled section.
The electric signal output from the second light-receiving element is input to the second control section, and the instruction decoding means decodes the electric signal into the control instruction. Based on the decoded control instruction, the operation control means controls the operation of the main apparatus.
On the other hand, when the remote-controlled section communicates information to the remote operation section, the transmit signal generation means of the second control section generates a digital signal corresponding to the information communicated to the remote operation section, and this digital signal is output to the second transmission section as a transmitted digital signal. This digital signal is input to the second light-emitting element of the second transmission section, and the second light-emitting element emits light based on the signal. Furthermore, the third linear-polarization plate radiates the light emitted from the second light-emitting element to the external space as linear polarization.
The linear polarization emitted to the external space via the third linear-polarization plate (hereafter referred to as the xe2x80x9csecond signal lightxe2x80x9d) reaches the remote operation section, passes through the second linear-polarization plate of the first reception section, and enters the first light-receiving element. Then, the first light-receiving element converts the second signal light into an electric signal and outputs this signal. This electric signal mostly corresponds to the digital signal communicated from the remote-controlled section to the remote operation section.
The electric signal output from the first light-receiving element is input to the first control section, and the information decoding means decodes the electric signal into the receive information. Moreover, the display control means displays on the display section the receive information decoded by the information decoding means.
In addition, the polarization surface of linear polarization radiated to the external space from the first transmission section of the remote operation section is orthogonal to the polarization surface of linear polarization radiated to the external space from the second transmission section of the remote-controlled section. This configuration prevents the linear polarization radiated from the first transmission section from passing through the second linear-polarization plate of the first reception section while preventing the linear polarization radiated from the second transmission section from passing through the fourth linear-polarization plate of the second reception section. This configuration thus precludes a mixture of these two signal lights from being received to prevent malfunction resulting from such a mixture.
This configuration also obviates the need to improve the light-emitting directionality of the light-emitting element and the light incidence directionality of the light-receiving element to eliminate the needs for cumbersome optical-axis alignment. Consequently, data can be communicated using either the half-duplex or full-duplex communication method by simply effectively opposing the remote operation section and the remote-controlled section to each other, so this configuration is practical. In addition, using the full-duplex communication method, long continuous data transfer can be easily achieved without the needs for complicated protocol control. Moreover, the information communicated from the main apparatus can be displayed on the display section of the remote operation section located on the operator""s side, thereby improving the operability of remote control and enabling information (for example textual information) to be displayed to extend the applicable range of the apparatus.
In addition, according to another configuration of the present optical remote control apparatus, the above bidirectional optical communication apparatus is adapted to provide various unique effects.